282 Responses to “Unforced variations: Aug 2015”

Consider Hansen’s claim polar melting is altering the oceans circulation with the result tropical waters will get warmer and produce stronger storms, while higher latitudes will be cooled by the melt water on the surface.

Consider thermal stratification is cutting phytoplankton, which are the base of the ocean food chain and the lungs of the planet off from the nutrients they need to survive.

Changing the thermal structure of the global ocean is what is required to remedy these threats.

The oceans from 500 to 2000 meters are warming by about .002 degrees Celsius every year, and in the top 500 meters, they’re gaining .005 degrees C. In contrast the atmosphere has been warming about 3 times faster than the deep ocean and the poles 3 times faster than that. It is apparent therefore that the deep oceans have the greatest capacity to accept the heat of global warming while producing the least temperature increase because of their huge heat capacity.

Swapping these two figures around would be hardly the same concern as induced acid rain.

If climate change can’t be addressed on the basis of sound science and natural expample, then all hope is lost as would be the point of this blog since the 6th extinction event would be inevitable.

84: “The most recent NASA study confirms the hiatus was real and that the heat that went missing from the atmosphere was trapped in the waters of the Pacific and Indian oceans to a depth of about 300 meters instead. The Pacific Ocean was the primary repository of this heat as unusually strong trade winds piled up warm water in the west, pinning it against Asia and Australia but those waters became so warm some of the heat leaked into the Indian Ocean.”

Did any climate models predict that this non-linear heat trap in the oceans might happen? My guess is no, and that is the kind of thing that concerns me about the climate modeling. I realize that the climate system is very large and dynamic, but it seems like there might have been some model out there that would/should have suggested that the oceans might react to warmer global temperatures in this way.

Before one attempts to redirect surface heat to 1000 m depths, a relatively daunting task in the open ocean, shouldn’t we try removing excess heat from certain “hot-spots” (e.g. Phoenix AZ and other cities) at the surface by sending the “hot air” into the upper troposphere where it can be allowed to immediately radiate heat back into outer space with greater efficiency than in the lower troposphere? An Atmospheric Vortex Ventilator could accomplish this with a minimum number of “moving parts” resulting in much lower investment costs and operating headaches. I’m not saying it would be enough, but would certainly be the easiest place to start if one wants to get rid of excess surface heat that is having adverse health effects (e.g.,on the inhabitants of said “hot-spots”).

And if you nudge a climate model in the tropical Pacific to follow the observed sequence of El Niño and La Niña (rather than generating such events itself in random order), then the model reproduces the observed global temperature evolution including the “hiatus” (Kosaka and Xie 2013).

AGW-deniers might say that Kosaka and Xie obtained their close fit to the observed temperature curve by tuning their model to fit the data, but all K&X did was match the actual timing of ENSO events rather than randomizing them, in an otherwise standard physics-based model.

Kosaka and Xie find that the POGA-H run reproduces the hiatus, along with most other interannual variations in global surface temperature (correlation 0.97 since 1970). In addition, it reproduces most of the key observed regional variations in warming, both during the rapid rise of 1971-1997 and the hiatus period of 2002-2012. All of this, to me, is convincing evidence that any explanation for the hiatus must pass through the tropical central and eastern Pacific.

Sounds to me like a step toward improving the models, just as we would expect to happen over time.

Heats pipes work in any orientation to gravity. It is the pressure differential between the evaporator end and the condensing end of the pipe that drives the movement of the vapor. With conventional, as in small heat pipes used to move heat in your computer away from the CPU, the condensed fluid is returned to the evaporator by wicking which still works upside down over a short distance but off course would not work over 1000 meters. It is necessary to pump the condensed fluid back to the surface The Prueitt patent “Heat transfer for ocean thermal energy conversion” shows the parasitic loss for pumping ammonia for such a system is about 7.5%

I am all for any system that will get rid of the heat. The problem is 93% of it is in the ocean and it is this heat that I think we have to address. The laws of thermodynamics say there is only two things you can do with it. Covert it to another form of energy or move it somewhere colder. Heat pipe OTEC does both in a ratio of about 1 to 20.

James Lovelock said in a Nature interview, “We shouldn’t have forgotten that the system has a lot of inertia and we’re not going to shift it very quickly. The thing we’ve all forgotten is the heat storage of the ocean — it’s a thousand times greater than the atmosphere and the surface. You can’t change that very rapidly.”

The facts that the models didn’t predict the hiatus and that the scientists all forgot the heat storage of the ocean, are why, to my mind, the solution has also been overlooked.

It seems to me this forum is the best place to rectify that situation.

As my slightly garbled comment above (sorry about that!) indicates, I think it’s pretty much a damp squib. Part of the ‘magic’ of M15 consists in ignoring the instrumental record completely in favor of the satellite record and especially RSS–let alone the apples-to-apples issue addressed by Cowtan et al’s “Robust Comparison of Climate Models” here:

To be fair to M15, I’m not implying that they *should* have addressed Cowtan et al.; since it came out only a week before “Keeping It Simple”, that was obviously ‘not on.’ But “Robust Comparison” definitely bears upon the point at issue.

RE #104 & Did any climate models predict that this non-linear heat trap in the oceans might happen? My guess is no….

The answer is yes, sort of. That is, Hansen, et al., in 1981 projected that if the heat went down into the deeper ocean waters, there would be less surface warming…..See p. 960 of his “Climate Impact of Increasing Atmospheric Carbon Dioxide” at http://pubs.giss.nasa.gov/abs/ha04600x.html It actually underestimated the warming with this “mixed layer & thermocline (=infinity)” effect & the “mixed layer & thermocline (k=1 cm2 sec-1)”

I use this when denialists say the models don’t predict, focusing esp on Hansen’s 1988 model….. But of course they all say that the heat is not going into the ocean, but rather it is the ocean heat that is causing our current warming :)

“… the National Weather Service inspects ASOS sites every 90 days to conduct preventative maintenance. Prior to Monday, Reagan National’s last check was on June 9 when there was only a 0.4-degree difference between the temperature sensor and the psychro-dyne reference measurement.

Lee explained that the temperature measurement at an ASOS site is within technical specification as long as its temperature readings are within (plus or minus) 5 degrees of the reference measurement. Both the ASOS and the psychro-dyne sensors have an error of plus or minus 1.8 degrees. Lee noted that, even though he decided it was time to install a new sensor Monday, Reagan National’s temperature readings had not strayed from specification then or on any prior inspection….
…
… whenever a new record is set that is within a couple degrees of a previous record, it may or may not actually be a record.

Hilarity will follow.

Time to revive — as simply as possible for the fifth grade literacy level — the explanation how data taken from a thousand thermometers can be more informative about what’s happening than data taken from one single thermometer.

“UK Foreign Office computer climate and economic models predict that, given no major policy changes worldwide, global warming could collapse the world economic system by 2040″

Comment by wili — 9 Aug 2015

I looked for this statement as well and came up with nothing. Google Scholar and other searches.

My question is this…. does the speed at which Global Average Temperatures rise depend on climate sensitivity? My understanding is that we don’t know exactly how sensitive the climate is toward CO2, therefore we do not know how fast things will heat up. We have ‘educated guesses’ but no way of knowing if we’ll reach the 2C mark in 10, 20, or 30 years. Do I have this right?

Ultimately I’m wondering, given how much CO2 is already in the atmosphere how quickly we’ll get to the 2C mark. I have a feeling that the process is accelerating exponentially, the same with ice melt etc.

It would be interesting to know which situations you regard as “denial”. For instance, let’s say we meet again in 25 years and people around the world are not dying by the millions every day because of climate change. Would it be denial to say “yes, in 2015 I believed that billions would die in this decade, but the decade isn’t over yet”? Or another five years without mass dying “I was just a bit off with the timing, but it’s going to happen soon, in a couple of decades for sure”? Another such fifteen years “Next decade!”?

An observation: In the impacts/adaptation article that you linked the word “could” occurred more than 3 times as often as the average for English. Science should avoid that word.

SK: It would be interesting to know which situations you regard as “denial”. For instance, let’s say we meet again in 25 years and people around the world are not dying by the millions every day because of climate change. Would it be denial to say “yes, in 2015 I believed that billions would die in this decade, but the decade isn’t over yet”? Or another five years without mass dying “I was just a bit off with the timing, but it’s going to happen soon, in a couple of decades for sure”? Another such fifteen years “Next decade!”?

BPL: If my calculations are correct, there is a 67% chance civilization will collapse between 2022 and 2034, and a 95% chance it will collapse between 2016 and 2040. I’m working on refining the estimate. If we get to 2040 and everything’s fine, it will be good evidence that I’m wrong.

My short answer is “Don’t know.” The long answer would probably boil down to much the same.

But I do have a few observations about the question that may be a bit helpful at least.

First, ‘climate sensitivity’ doesn’t mean just one thing:

In practice, people often mean different things when they talk about sensitivity. For instance, the sensitivity only including the fast feedbacks (e.g. ignoring land ice and vegetation), or the sensitivity of a particular class of climate model (e.g. the ‘Charney sensitivity’), or the sensitivity of the whole system except the carbon cycle (the Earth System Sensitivity), or the transient sensitivity tied to a specific date or period of time (i.e. the Transient Climate Response (TCR) to 1% increasing CO2 after 70 years). As you might expect, these are all different and care needs to be taken to define terms before comparing things (there is a good discussion of the various definitions and their scope in the Palaeosens paper).”

Note, in particular, the differing definitions with respect to time, such as the 70-year term of the example of TCR, versus ‘equilibrium sensitivity’ which (AFAIK) need not have a particular definite time frame attached (although its characteristic time scale will be way, way longer than for TCR.) So your question would need to have *which* sensitivity was most relevant. (If you are talking about decadal timespans, TCR might be your choice.)

Next, note the figure in the linked RC article–it illustrates how various feedbacks operate over various timescales. I’d venture to guess that there is no guarantee that those feedbacks will necessarily operate proportionately over time or space. As a (totally made up) example, imagine that the vegetation feedback is highly non-linear, such that CO2 fertilization gives a negative feedback for low levels of warming as plants take up the CO2 enthusiastically in a regime such as the current one, but that plant mortality increases sharply at, say, 1 C warming, turning the feedback positive.

In that case, you’d think that the warming curve would be muted at first, but would turn sharply upwards. But notice that the feedback is sensitive to different things: CO2 concentrations at first, then temperature second. That implies that, at least in principle, higher emission rates might initially produce *lower* warming rates, since temperature response is lagged by comparison with CO2 response. Later on, of course, it would be quite a different story: as the imagined temperature threshold was reached and positive vegetative feedback became the dominant driver, the increase might become such that you’d once again get greater net warming at some point in time.

(Note that I’m not saying that this happens, or could happen, in reality–it’s just something made up that sounds plausible enough on the surface to illustrate a larger point.)

So, it’s clearly a complicated business. One final observation: my sense is that the general approach usually taken isn’t the one you lay out, in which assumed sensitivity values are used in straightforward calculations to arrive at relatively clear timeframes for temperature ‘X’. Rather, the usual strategy is likely to be that warming trajectories are modeled in GCMs for various forcing scenarios, and that ensembles of these will allow estimated of sensitivity AND of warming by ‘date X.’ In general, sensitivity isn’t programmed into GCMs; rather it ’emerges’ from the modeling exercises.

(Though there are numerical models of various things that allow the use of assumed climate sensitivities as inputs.)

I hope that helps, and that the more knowledgable will correct anything I’ve said that’s egregiously wrong or misleading.

114 Hank said, “Time to revive — as simply as possible for the fifth grade literacy level — the explanation how data taken from a thousand thermometers can be more informative about what’s happening than data taken from one single thermometer.”

Give a lousy dart player one dart and tell him to hit the bullseye. Odds are that the resulting dart will be a bad estimate of the bullseye’s position. Give that player 1000 darts. Odds are that averaging all of them will give a good estimate of the bullseye’s position.

You are undoubtedly correct in pointing out where most of the “excess heat” is being stored. My concern is that even if the OTEC process you describe is “efficient”, the area over which it would have to be deployed is far beyond the ability of our economic systems, and the “political will” to make it is just not there, nor will it be.

Besides, the more immediate problem is “losing the arctic”, which, if it occurs at current rates, will totally negate efforts made elsewhere. The arctic is a much smaller area than the oceans, making it a more “doable” endeavor, at least when compared with the OTEC scheme.

My suggestion is that we focus our resources on enhancing heat removal (minimizing loss of albedo) by curtailing air traffic above 45 deg N. during the winter months, and cooling northward flowing rivers in Siberia,by spraying the northward flowing water into the base of hundreds, if not thousands of Atmospheric Vortex Ventilators. The cloud and snow cover created by condensation aloft during shoulder months has the potential to increase albedo near the rivers.

“BPL: If my calculations are correct, there is a 67% chance civilization will collapse between 2022 and 2034, and a 95% chance it will collapse between 2016 and 2040. I’m working on refining the estimate. If we get to 2040 and everything’s fine, it will be good evidence that I’m wrong.”

I read the paper you linked to and it gives essentially no evidence in support of such a claim. It primarily consists of a nonsensical and simplistic extrapolation of a drought index which reaches 100% quite quickly, even though the actual risk of drought in most areas is quite low. When one’s conclusions are physically impossible, one is best served by rethinking, especially when your analysis is pure-t-curve-fitting and extrapolation. There’s absolutely no science or physics in your paper. Not even a hint. It looks like a narrow-minded mathematician’s attempt at science. Now, had you said that the combination of drought and flooding would wreck our system, then perhaps you’d have a scientific leg to stand on. In a warming world, drought is severely limited by globally increased rainfall.

Drought will probably increase. Snow melt will definitely reduce its service in feeding rivers beyond spring. I’m rather certain that people will take action to respond to such problems, say, by building dams or moving agriculture to currently untenable areas which will become suitable for agriculture. I’m confident that many millions will die or be brain-damaged during the transition. But unless you have more data or analysis, I’ve got to rate your conclusion as scientifically poor. You simply don’t provide evidence, let alone prove your point. I’m not saying “we disagree”, but “you’re spouting nonsense”.

I’m old enough to have learned that sometimes I just don’t get it. Sometimes “common sense” gets in the way of scientific truths. As such, I’m quite open to learning and changing my mind. Enlighten me. So far, you’ve quibbled around the edges, but not responded to a single major point. I invite you to do so by explaining how drought will almost immediately increase to 100% of the planet’s agricultural lands and no new agricultural lands will open up even though rainfall is increasing and there’s zillions of acres of currently unproductive land in the arctic. (Or by explaining that that’s not what you’re saying) In science, one has to provide a mechanism which hypothetically causes the conclusion. You give no plausible mechanism, so your theory is rubbish. Math ain’t science.

Millions of years ago the world was hotter. But instead of a drought-stricken moonscape, the planet was busily growing so much more than could be consumed that fossil fuels in incredible amounts were being laid down. Why do you think that this time will be different?

An observation: In the impacts/adaptation article that you linked the word “could” occurred more than 3 times as often as the average for English. Science should avoid that word.

Comment by Steinar Midtskogen — 12 Aug 2015

The scientific creed is: “I could always be wrong” but that doesn’t mean you can take any comfort in finding the words ‘could’ or may’ in any assessment of our dire situation. There are always uncertainties involved in scientific research but THAT DOESN’T ME WE DON’T KNOW ANYTHING.

It’s obvious to me that you don’t understand basic scientific principals. Yellowstone WILL erupt again. Now it ‘could’ erupt tomorrow. The point is we KNOW it WILL ERUPT AGAIN. Wanna go build you a house next to Old Faithful? We KNOW sea levels will rise. We KNOW roughly how much. Do you wanna take out a 30 year mortgage on some beachfront property in Miami? Go ahead. Be my guest. I happen to know people with really nice houses in Coal Creek Canyon, CO. that were totally wiped out two years ago by massive flooding. They’re trying to build back adding huge boulders to fortify their property against the possibility of more massive flash flooding. Guess where those boulders will end up? You’re not gonna stop a wall of raging mud with a few boulders.

Being willfully ignorant is expensive and deadly. That doesn’t stop people from being willfully ignorant. We’re in serious trouble. ALL branches of the military, the Department of Defense, the Pentagon, President Obama, Munich Re, NOAA, NASA, the EPA understand this. They KNOW what’s coming. If you want serious answers you need to ask serious questions and do your homework. That’s what I’m trying to do. It takes a while to really wrap your brain around our situation but if you’re serious and listen you will begin to understand how it all works and why we know what we know. BPL addressed your questions. Listen to what the man’s telling you.

This course DelftX: NGI101x Next Generation Infrastructures
courses.edx.org/ Delft university.
has stuff called “Actor analysis.” They make graphics of who has the power to help or hinder and who wants to help or hinder. The analysis tells you who you should really go to for help doing something and who you should ignore or stay away from. It might be useful here.

It seems to me that a critical number we need to have is the climate/temperature sensitivity of the global food production and distribution system. The world has long passed the point where the population can be supported by subsistence farming, so the continued robustness of the the production system is required. Also, the question of how the system performs when demand exceeds supply is an interesting question. Normally one would think that prices would rise and those with less money are screwed, so that tells you the likely first impacts of any overall reductions in production. I feel like there must be a significant literature on this, but being outside my field, I am not aware of it. A little library work would probably be interesting.

> Give that player 1000 darts….
No, because it’s not repeatable. If each individual dart, every day, had the same error — that would be analogous to the situation with thermometers.

Each one is “plus or minus” consistently — except when it starts to fail, and that’s what apparently happened at Reagan airport’s weather station. The thermometer was within the (rather wide) error allowed on one check; next time it was much farther off (still within the rather wide error allowed, but going bad — I guess).

I know the work done to check these thermometers and detect that sort of failure — by comparing a trend in one to what its neighbors are doing.

Just saying — I’ve never yet seen a good fifth-grade explanation. Hoping for it.

And last I heard the US voter average is reading at fifth grade level, and that’s for general reading. For scientific reading — we’ll see.

Republican members of the House Committee on Science, Space and Technology wrote to Environmental Protection Agency administrator Gina McCarthy and called her testimony at a hearing in July “false and misleading.”

On July 9, McCarthy testified to the House Committee on the transparency of the EPA’s regulatory agenda. Members of the committee asked McCarthy about the “secret science” that goes in to justifying EPA regulations because they want to ensure the data is available to the American people.

Rep. Frank Lucas (R., Okla.) asked McCarthy whether the agency had made data that was used to craft the Waters of the United States (WOTUS) rule public. While McCarthy said that the information was “available,” the Committee maintains that EPA did not provide any scientific or legal justification for the figures Lucas asked for.

“Your statement that the information and data requested in Mr. Lucas’ question was publicly available in the EPA docket was false and misleading,” the committee wrote. “Based on the Corps’ memorandum, it is apparent that the figures outlined in EPA’s final WOTUS rule were completely arbitrary and not based on any science.”

The letter cites three more examples during questioning at this particular hearing where the Committee deemed McCarthy’s statements either false or misleading.

It was at this same hearing that McCarthy said she did not know the percentage of CO2 in the atmosphere, information fundamental to EPA’s regulations.

“Providing false or misleading testimony to Congress is a serious matter,” the committee wrote. “Witnesses who purposely give false or misleading testimony during a congressional hearing may be subject to criminal liability.”

“With that in mind, we write to request that you correct the record and to implore you to be truthful with the American public about matters related to EPA’s regulatory agenda going forward.”

“Millions of years ago the world was hotter. But instead of a drought-stricken moonscape, the planet was busily growing so much more than could be consumed that fossil fuels in incredible amounts were being laid down. Why do you think that this time will be different?”

Comment by Richard Caldwell — 12 Aug 2015

You are a piece of work. You have no knowledge of basic Physics or Paleo history. I’m not the sharpest knife in the drawer but you take the cake. No wonder we’re in trouble.

“The relationship between mathematics and physics has been a subject of study of philosophers, mathematicians and physicists since Antiquity, and more recently also by historians and educators. Generally considered a relationship of great intimacy, mathematics has already been described as “an essential tool for physics” and physics has already been described as “a rich source of inspiration and insight in mathematics”.

This Scientific American article might be of interest. Michael Mann estimates that we’ll cross the 2C barrier by 2036.

Comment by Tony Weddle — 13 Aug 2015

Thanks Tony. I’ve read that article and I think he mentioned 2036 or so under a BAU scenario. Given the speed at which things are happening I still tend to think that’s an underestimate. He also said if we reach 404ppm if I remember correctly. Well we’re already there. He also pointed out that GAT would not be evenly distributed since the poles heat up much faster. I forget all the various figures he cited. Not to mention a lot of heat is coming out of the Pacific right now. I would be interested to hear the very latest projections to see if they’ve changed and by how much.

On another note I saw where they released thousands of black plastic balls into a California reservoir to slow down the rate of evaporation. Was Black really the smartest color to use since black absorbs heat? Also, what happens when the plastic starts to breakdown into smaller pieces? Plastic is also a petroleum product. I don’t see this as being a very smart idea. Thoughts?

Hank said, “No, because it’s not repeatable. If each individual dart, every day, had the same error — that would be analogous to the situation with thermometers.”

Good point. So, take a robotic Artificial Intelligence and watch a lousy player throw 1000 darts. Then move the dart board a bit and have the robot throw exactly as erroneous throws at the new target. NOW you have that 5th grade explanation (I think)

I commented on losing the arctic in last months variations section at #255.

To summarize; Hansen suggests the oceans are experiencing a greenhouse effect of their own. Melt water is creating a blanket that will flow over the warm layer moving towards the poles. This blanket prevents the loss of heat to the air (that you wish to promote) and the trapped heat then works on the underside of the ice shelves and glaciers; increasing their melt rate and sea level rise. He says the accumulating cold water on the surface will also shut down the Thermohaline with the result tropical waters will get warmer and produce stronger storms, while higher latitudes will be cooled by the melt water on the surface.

Another current study by a team lead by Samuel Doyle of Aberystwyth University, says the melting of the Greenland ice sheet is being amplified by rainfall on the ice surface driven by late-summer cyclones. Since this too will produce the effects Hansen notes, including stronger storms that will in turn produce more late summer rainfall in Greenland, this doubly negative feedback may even produce greater and faster sea level rise than even Hansen has projected.

Heat moved to the deep in the tropics is no longer available to warm the atmosphere, melt ice or drive storms.

This is OT, but I am concerned about what is going on at Dot Earth. I had not ben there for a while, and was surprised to find that Andy is allowing wmar to publish his scandalous lies about Hansen, the whole climate science field, climate scientists in general, and the IPPC in particular. Susan Anderson is commenting in the same thread, but does not challenge him, so I assume she realizes it is futile. Why is Andy allowing a troll like wmar to pollute his blog this way? If it is acceptable to engage in such unsupportable ad hom attacks with impunity, I will not be wasting time there.

“There is only one global ocean,” as NOAA likes to say. While it’s changing in different ways and to different degrees in different places, it’s a single, huge, interconnected system….
…
… it’s worth taking a look at the changes reshaping the body of water that defines our planet, and examining where our best predictive sciences say we’ll end up at the end of the century—in the year 2100, which is as good a benchmark as any. It’s a natural milestone, included in a lot of climate models’ projections, policy-oriented synthesis reports, and research-based recommendations for political leaders.

By combing through the most recent science and reaching out to oceanographers and climate scientists, I tried to render a snapshot of what the future of our oceans might look like.

GISTEMP is reporting the warmest July on record for 2015, at +0.75ºC the 32nd hottest anomaly on record. The rolling 12-month average is now above +0.8ºC at +0.8025ºC. This compares with 2014 (the warmest calendar year on record) that sits at +0.739ºC. Scorchio continues apace.

RC, apparently in a bad mood: I read the paper you linked to and it gives essentially no evidence in support of such a claim. It primarily consists of a nonsensical and simplistic extrapolation of a drought index which reaches 100% quite quickly, even though the actual risk of drought in most areas is quite low. When one’s conclusions are physically impossible, one is best served by rethinking, especially when your analysis is pure-t-curve-fitting and extrapolation. There’s absolutely no science or physics in your paper. Not even a hint. It looks like a narrow-minded mathematician’s attempt at science.

BPL: Actually, I discussed A) why drought could not really reach 100%, and B) what the physics behind the problem were. Apparently you missed both.

The science behind rising drought with global warming has to do with changes in the distribution of rainfall. In brief, continental interiors dry out, coastlines get soaked. While it is impossible for drought to go to 100% of land area, it is not at all impossible that it could get to a (so far undefined) critical level where global civilization would collapse.

The simulation was not pure curve-fitting at all. As I said in the paper, citing sources, there is a feedback between drought and warming. Warming leads to drought by the changes in circulation I mentioned. But drought also leads to warming. A large area in severe drought has very little soil moisture, and crops and other plants do not do well. Therefore, there is less evapotranspiration to cool the surface. This effect was first noted for the Sahel drought by Courel et al. in a paper in Science in 1984.

The simple fact is that the fraction of Earth’s land surface in severe drought doubled between 1980 and 2010. Another simple fact is that the growth is not linear. That’s the empirical evidence. Fit it to whatever theory you’d like. I imagine the actual curve will turn out to be sigmoid, AS I DISCUSSED IN THE PAPER.

The question is whether global civilization can survive with 40% or 70% of land in severe drought–keeping in mind that global warming causes OTHER problems for human civilization as well, like mass extinctions, ocean acidification, increased heat waves, decreased fresh water supply from glacier-fed rivers, more powerful storms, etc. It’s not drought in isolation that’s the problem. Which I ALSO said in the paper.